The dungeon felt a little off, even from the beginning. A little... a little fuzzy around the edges, like the spaces where they weren't looking were rearranging themselves just a bit. It was one of those dungeons that rearranged itself at semi-regular intervals, but it still made sense, physically. All of the pieces were being rearranged, but they were still the same.
Until they weren't.
It was right as they were closing in on the core. Another dungeon had sprung up, and this A-rank dungeon had been predictable enough that they decided to let Yun Minseo depart early to prep for looking at that one. It's not clear if it was feeling threatened by the pair of super powerful combat espers closing in on its core, or if it was waiting for the much less obviously threatening sensor to leave, but, well. That was when it went from 'tricky and annoying but doable' to. Whatever the fuck this is.
Walls of iron turn to sludge around them. The ground shifts from stone to mud to something else, something stickier, at their feet, and then drips down the ceiling to attempt to cover them in some sort of horrible tar as their comms suddenly die. A swarm of something with the wings of birds and the heads of dogs and the claws of some kind of velociraptor comes barreling out of the sludge, a great tidal wave of teeth and claws and malice. The sludge around them writhes and turns to something like snakes, each one's body as sharp as knives, twitching and stretching in unexpected directions.
That is not to say that Tae-gun and Hye-jin take this lying down and go, "Oh well, the dungeon isn't what we expected. Time to give up and go home." Obviously, they're not doing that. Tae-gun can keep them above and protected from whatever fresh new bullshit this fucking - sludge dungeon - throws at them, and whatever the fuck this stuff is made of, Hye-jin can actually just melt it away with a truly astonishing amount of fire. They can still win this, still find and destroy the core.
It just means that - well. Here they are. It's started.